The present invention relates in general to heat exchangers and in particular to a new and useful modular arrangement for the shipment and assembly of heat exchanger units.
In recent years, Heat Recovery Steam Generators (HRSG's) have usually consisted of a vertically oriented heat exchanger comprising spirally-finned tubes located inside an externally supported box type structure. High temperature turbine exhaust gas passes through the box and over the tubes in order to recover the heat from the gas.
For economic reasons, it has been common practice to incorporate a modular type design which utilizes a shop fabricated and shop assembled heating surface arrangement. Larger HRSG's are generally two or more modules wide.
Known modular arrangements typically comprise a finned tube heating surface that is bundled complete with top and bottom headers. For ease of handling, these modular shop assembled packages are assembled with an integral shipping truss assembly built of commercially available structural steel shapes.
The finned tube heating surface is shipped in a horizontal position and rotated at the erection site to a vertical orientation. When in its final position, support for the heating surface is normally provided by base frame steel which comprises a part of the shipping truss assembly.
The known box type structure designs comprise internally insulated and lined casing panels which incorporate a cold casing design. These panels can be either a part of the shipping module or they can be installed after the HRSG pressure part modules have been placed in their final position. Column steel attached to these panels provides the overall strength and stability for the total HRSG structure by providing side to side as well as fore and aft restraint against potential loadings which could occur as a result of wind and seismic conditions.